(a) Field of the Invention
The present invention relates to a gear box for driving a hydraulic pump provided in an extra-large sized excavator and the like.
(b) Description of the Related Art
In general, a plurality of gears are arranged in a transmission, such as an accelerator, a decelerator, and the like, provided in various driving devices such as a vehicle, a generator, and the like to transmit driving force input through an input shaft to an output shaft by increasing/decreasing the driving force, and the transmission is typically referred to as a gear box.
Prior to actual use of such a gear box, the gear box should satisfy a performance test according to a number of requirements, that is, durability and precise torque transmission characteristics of the gear box.
In particular, large-scaled equipment such as an extra-large sized excavator generates loud noise when driving a hydraulic pressure pump mounted to the gear box, and accordingly, a means for reducing the noise is required.
A configuration of a conventional gear box mounted to large-scaled equipment such as an extra-large sized excavator is as follows.
In general, in an extra-large sized excavator (e.g., with a vehicle body weight of greater than 90 tons), three or more hydraulic pressure pumps are provided per single engine driving shaft to operate a hydraulic system, thereby reducing fuel consumption.
Such a gear body of the extra-large sixed excavator is provided with a plurality of gears formed of driving gears and driven gears in an outer case. In addition, when the gears are partially rotated with a predetermined depth from an internal bottom of the case, lubricant stored in the case lubricates the gears while they rotate.
In such a gear box, when the plurality of gears provided in the gear box rotate, the lubricant is churned by the rotating gears such that a lubrication portion expands to a portion not submerged by the lubricant, and accordingly the gears can smoothly rotate.
However, in the conventional gear box provided in the extra-large sized excavator, the lubricant is churned by the rotating gears such that the lubrication portion expands to the portion not submerged by the lubricant, but other portions cannot be lubricated.
Further, since a portion where the lubricant is not supplied is relatively large in the conventional gear box, friction noise due to a power transmission error of the gear is increased, and loud load noise occurs due to friction between gears rotating at a high-speed and air or due to vibration of a shaft system or structural vibration.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.